The invention relates to an implant that has a variable axial length and that is suitable for the application in spinal or trauma surgery. The implant includes a first member and a second member guided relative to the first member to be movable relative thereto in an axial direction for adjusting an overall length of the implant. Further, the implant includes an engagement member. In a first configuration, the engagement member is configured to engage the first member and the second member to lock the first member with respect to the second member. In a second configuration, the engagement member is configured to engage the first member but not the second member so that the second member is movable with respect to the first member. The engagement member is inhibited from disengaging from the first member.
An implant in the form of a length adjustable spacer for insertion between two vertebrae is known from U.S. Pat. No. 6,200,348 B1. The spacer comprises a first sleeve-shaped member and a second sleeve-shaped member which is slidably guided within the first member in an axial direction relative thereto for adjusting the overall length. The second member comprises on its outer surface facing the first member an axially extending portion having ratchet notches. The first member comprises an engagement member that cooperates with the ratchet notches for displacement to a desired overall length. The engagement member is formed by a tool that comprises a resiliently biased ball on its front face that is configured to engage the ratchet notches. After adjustment of the suitable axial lengthy a locking screw is used to lock the first and the second member relative to each other and the tool is removed.
Another spacer for insertion between two vertebrae is known from U.S. Pat. No. 7,803,191 B2. It comprises a first tubular member and a second tubular member. The length of the spacer is adjusted by telescoping the second tubular member out of the first tubular member using a tool and once the desired length is achieved, one or more locking screws are inserted to lock the second member relative to the first member.
A further length adjustable intervertebral spacer is known from. U.S. Pat. No. 8,241,363 B2. The spacer comprises a pair of coaxial annuluses locked together by an engagement member comprising a set screw and a pressure plate having an outer face contacting the set screw and an inner face having teeth adapted to mate with ratchet notches of the second member.
Another implant in the form of a length-adjustable bone plate is known from U.S. Pat. No. 5,964,762. In a similar manner as for the above described spacers, a first plate portion is slidably arranged relative to a second plate portion using a tool and the desired length is fixed with locking screws.